Asynchronus CPU FSB vs. RAM FSB advantageous?

[markjs]

I have PC 2100 that just doesn't want to overclock and I have been told there is no advantage to running the ram out of synch with the CPU FSB. I have tested the CPU Arithmatic and Multimedia performance in SANDRA, and they are the same whether the processor is set at a 200MHz FSB or at 133MHz, but the memory bandwidth seems to be signifigantly improved when the CPU is at 200MHz FSB and the Ram is still at 133. I am wondering is this just a benchmarking anomaly, or is that bit about processor bus speed not mattering and being bad for performance when it's out of synch just nonsense?

 

[mechBgon]

Sandra is trash.

(there, got that outta the way )

Do some UT2003 Demo Botmatch runs at low resolution and see what happens. I tried a test where I ran my AthlonXP2500+ at its proper 166MHz bus and then did one run with the RAM sync'ed at 166, and another run with the RAM out-of-sync at 200MHz.

Result: 20% lower framerate in Botmatch when out of sync.

Bigger picture: why not buy yourself some PC3200 or higher, and sell your PC2100 in For Sale & Trade? You can re-use the PC3200 later if you upgrade to an Athlon64.

 

[markjs]

I don't have UT2K3 so I did some benches in Doom 3 and with the ram in synch I got 32.2 fps and I got 32 with ram out of synch.....so that didn't tell me much.

 

[markjs]

I have just run 3DMark 2003 and got 4036 with the CPU bus at 133 and 4106 with the bus at 200 so it must be an anomaly with UT 2K3 that makes it like the in synch bus speed.

 

[mechBgon]

Originally posted by: markjs
I have just run 3DMark 2003 and got 4036 with the CPU bus at 133 and 4106 with the bus at 200 so it must be an anomaly with UT 2K3 that makes it like the in synch bus speed.

I think what you're seeing is that no matter what speed your CPU is running, it's limited by the memory bandwidth because you're keeping your memory down at 133MHz. If you'd like to try for more performance, see if you can persuade your memory to run 166MHz and try the CPU and RAM sync'ed at 166MHz. Bet your real-world benchies will go up, if it can be persuaded to run stable like that.

 

[Vee]

I always have it the other way. Faster RAM than FSB, so I always run in sync, and I haven't personally tested this. - But, I'm convinced it's always better to run the FSB as fast as possible. Running RAM slower out of sync, is probably just fine. It's the other way, running RAM faster than FSB that is questionable.